Most ophthalmic medicaments are topically administered to the eye. The most common dosage form for such medicaments is liquid drops. The liquid drop form is easy to apply, but suffers from the inherent disadvantage that the drug it contains is rapidly washed from the precorneal ocular cavity by tear flow. Thus, a continued sustained drug level is not obtained. Sustained levels are typically attained by periodic application of the drops, but this results in frequent administrations by the patient. The result of frequent administration and washing by tear flow is that the level of medication surges to a peak at the time the drops are applied, then the drug concentration falls rapidly.
Other methods of applying ophthalmic medicaments are the unitary ocular inserts. While such inserts deliver the drug in a sustained manner, they suffer from the disadvantages of being difficult to insert and remove, and are expensive.
The prior art discloses a polyvinyl alcohol-boric acid-iodine complex useful in the treatment of eye infections. [Klin. Oczna., 36 (1), 27-32 (1966), C.A. 67:72404r.] However, the researchers concluded that the complex must be maintained at a pH of 5.0-5.5 to afford stability of the iodine. At this pH, the complex is a conventional solution dosage form. Also, this pH is not compatible for use with injured eyes.